This invention is related in general to microelectronic device fabrication and more specifically to fabrication of a microelectromechanical system (MEMS) microphone including signal processing circuitry on a common substrate.
MEMS devices are desirable because of their small size, potential lower cost, and higher performance. Some types of devices that have been built using MEMS techniques include accelerometers, gyroscopes, temperature sensors, chemical sensors, AFM (atomic force microscope) probes, micro-lenses, combdrive actuators, piezoelectric actuators, etc. Such devices can be integrated with microelectronics, packaging, optics, and other devices or components to realize complete MEMS systems. Some examples of MEMS systems include inertial measurement units, optical processors, sensor suites, and micro robots.
Although MEMS techniques, and other related fields such as nanotechnology, have been used successfully to fabricate many types of devices, there are still various problems to be overcome in manufacturing increasingly complex devices. For example, it is desirable to fabricate MEMS devices that include auxiliary electronics or circuits. If the circuits can be formed on the same substrate as the MEMS device, then advantages in smaller size, lower cost, and efficient manufacture may be realized. However, the combination of a MEMS device and microelectronic circuit on a common substrate can be difficult to fabricate due to microelectronic process limitations.